Exemplary embodiments of the present invention relate to a method and device for producing a valve device for an airbag.
German Patent Document No. DE 10 2007 052 246 A1 discloses an airbag for a motor car, having a supporting structure that can be moved from a storage position into a restraining position. The airbag further comprises a shell, by means of which a restraining volume of the airbag formed by the supporting structure is surrounded in its restraining position.
Depending upon the construction type, it is necessary for the restraining volume to fill particularly rapidly with, in particular, ambient air upon movement of the supporting structure into the restraining position in order to thus be able to receive and restrain occupants of the motor car particularly efficiently.
Exemplary embodiments of the present invention provide a method for producing a valve device for an airbag that facilitates the production of a cost-effective valve device, wherein the valve device facilitates advantageous filling of a restraining volume of the airbag with air.
A method according to the invention for producing a valve device for an airbag, having at least one substantially air-permeable textile layer, in particular a fabric layer, and having a film, comprises at least one step, in which the textile layer and the film are arranged reciprocally overlapping at least in areas in a deep-drawing tool.
Subsequently, in at least one further step the film is deep-drawn in deep-drawing regions by means of the deep-drawing tool, whereby a plurality of depressions of the film are formed. In addition the method according to the invention comprises at least one further step, in which the textile layer is connected to the film, in regions of the film differing from the deep-draw regions, by means of the deep-drawing tool. Due to the fact that the film is deep-drawn by means of the deep-drawing tool and also connected to the textile layer by means of the same deep-drawing tool, the method according to the invention can be carried out particularly favorably with regard to time and costs. This facilitates low production costs and thus low overall costs of the valve device and thus of the whole airbag.
The film and the textile layer are advantageously connected to each other at least substantially simultaneously with the deep-drawing of the film, whereby this keeps the production time and hence the production costs of the valve device particularly low.
In addition the valve device produced through the method according to the invention facilitates a particularly rapid flow of a medium, in particular air, through the valve device in a flow direction so that, for example, a restraining volume formed by a supporting structure of the airbag (which is also described as a framework structure) can fill particularly rapidly with the medium, in particular ambient air. In addition the valve device can at least substantially prevent a flow of the medium in a second flow direction contrary to the first flow direction so that the medium remains in the restraining volume at least substantially or can only flow as desired very slowly out of the restraining volume if a relatively high inner pressure builds up in the restraining volume, for example in case of an accident, due to the impact of an occupant against the supporting structure or the airbag. Such a high inner pressure would cause the medium, in particular the air, to flow out of the restraining volume in the second flow direction.
The valve device thus facilitates, for example, a particularly rapid movement, in particular unfolding, of the supporting structure from a storage position, in which the supporting structure is accommodated in a housing of the airbag, into a restraining position so that the supporting structure and possibly a shell surrounding the restraining volume in the restraining position can receive and restrain the occupant particularly efficiently. The valve device produced through the method according to the invention also guarantees a particularly good service life of the airbag so that it can thus protect occupant(s) particularly well from serious injuries.
It should be noted that the airbag can also comprise at least one air sack, which is to be filled with a medium, in particular air, and in which likewise the valve device produced through the method according to the invention can be used in order to facilitate a particularly rapid filling of the air sack with the medium so that the air sack can receive and restrain the occupant(s) particularly well.
The film of the valve device serves to at least substantially permit the flow of the medium through the valve device and thus the textile layer and corresponding regions of the film in the first flow direction and to at least substantially prevent the flow of the air in the second flow direction contrary to the first flow direction or correspondingly to allow a smaller air mass per time unit to flow through the valve device in the second flow direction than in contrast a higher air mass per time unit in the first flow direction through the valve device.
It is thereby facilitated, for example, that by deep-drawing, the depressions are formed as tubular valves that facilitate a flow of the film through these in the first flow direction. If the described high inner pressure in the restraining volume causes a flow of the air in the second flow direction, the tubular valves thus close (e.g., by coming come together), at least substantially, and prevent air from flowing out of the restraining volume at least substantially and slow down this flow correspondingly in the second flow direction. It is thereby understood that the film is at least substantially air-impermeable in other regions in which the depressions are not formed.
The textile layer of the valve device provides impact protection for the depressions formed, for example, as tubular valves so that they do not undesirably turn inside out when the air flows or tries to flow in the second flow direction, whereby this is at least substantially prevented by the closing tubular valves. By means of the valve device to be produced cost-effectively by means of the method according to the invention, a particularly advantageous valve functionality is thereby produced for the airbag.
The deep-drawing tool comprises, for example, cylindrical depressions whereby these depressions constitute negative counter contours in order to form the depressions as positive contours corresponding to the counter contours. The depressions of the deep-drawing tool respectively comprise at least one passage opening, in particular a borehole, whereby these are respectively arranged on a respective end face, in particular on a respective bottom, of the depressions of the deep-drawing tool. By means of these respective passage openings the depressions of the deep-drawing tool can be impacted with a pneumatic underpressure and thus at least substantially emptied so that the film for forming the depressions of the film can be sucked into the depressions of the deep-drawing tool and the film can thus be deep-drawn.
In order to deep-draw the film and to produce the valve device, the deep-drawing tool is advantageously initially covered with the film, on which the air-permeable textile layer is then laid for example as a supporting fabric.
The film and textile layer are thereby laid, for example, on a lower part of the tool. Subsequently the deep-drawing tool is closed by an upper part of the deep-drawing tool under high pressure, followed by the emptying of the depressions of the deep-drawing tool, so that the film is deep-drawn in a cup shape.
During and advantageously at least substantially simultaneously during the deep-drawing of the film, the connection of the film to the textile layer also takes place in regions of the film that are not or were not deep-drawn, thus between the at least substantially cylindrical depressions of the film that have already been formed, are formed during the connection or are formed following the connection. The film and the textile layer are connected, for example, by means of a bonding agent, mechanical pressure, and/or by heat, wherein, for example, the film is fused with the textile layer.
Further advantages, features and details of the invention ensue from the following description of preferred embodiments and by reference to the drawing. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and/or shown solely in the figures can be used not only in the respectively indicated combination but also in other combinations or alone without going outside of the scope of the invention.